Atrial fibrillation (AF) and ventricular tachycardia (VT) affect millions of patients in the United States. These arrhythmias can be cured with catheter ablation, but the arrhythmias often recur. The inability to confirm the presence of ablated lesions in the desired locations is the major factor in the greater than 30 % recurrence of AF after ablation. Additional limitations of current ablation technology include: (1) difficulty in navigating catheters to exact locations, making it difficult to accurately place ablations, and (2) the lack of ability to adequately predict the pathways of VT through scar, which are the targets for ablation. We are developing ways of combining the anatomic information from magnetic resonance imaging (MRI) and computed tomography (CT), with catheter ablation, for performing advanced real-time image guided interventions. It is not known, however, whether MRI or CT will be superior for image guided interventions. Both are included in this project because a number of the technologies being developed can be used with both MRI and CT. We hypothesize that high resolution imaging with MRI, and/or CT, with compatible electrode catheters, catheter-tip location sensors, remote-controlled catheter manipulators, real-time scanner control, thermal imaging, and 4-dimensional (3 spatial dimensions plus time) imaging software can (1) provide for accurate navigation of catheters, (2) provide the ability to titrate and confirm the presence of ablated lesions in the desired locations, (3) aid in producing more accurate electrical maps, and (4) aid in predicting the extent of ablation needed to eliminate the target arrhythmia. We have previously demonstrated the feasibility of (1) real- time MRI guidance of catheters, (2) lesion visualization using CT and MRI, (3) high resolution imaging of preserved myocardial tissue in scar, and (4) using computational modeling to predict the location of VT circuits. This proposal deals with developing (1) improved catheter tip location sensors, (2) improved real-time scanner control, (3) dynamic 3-dimensional image reconstruction, with superimposed catheter tip location information, (4) improved high resolution imaging of myocardium so that details of preserved myocardium within scar can be adequately visualized, (5) a computational model that can predict the VT circuits in individual patients based on the detailed scar morphology, (6) improved methods for predicting individual patient's response to ablation, (7) methods for real-time registration of multimodal information, including electrical maps, and multiple images, (8) MRI thermography to aid in real-time titrating and assessing of ablation lesion formation, and (9) remote controlled catheter manipulators to improve the accuracy of catheter placement. We will apply this technology to real-time advanced image guided therapy in patients with atrial and ventricular arrhythmias, and potentially broaden its use to interventional procedures in general. This project is a partnership between the Johns Hopkins University Departments of Medicine, Radiology, and Biomedical Engineering; and industrial partners (with cost sharing): Irvine Biomedical (clinical grade catheters), Hansen Medical (catheter manipulation system), and Imricor (catheter components).